Mobile devices such as smartphones and tablets are connected based on various RF technologies such as 5G, Wi-Fi, and satellite communication. Accordingly, as demand for RF products rapidly increases, Infineon’s RF products are expected to maximize system efficiency, satisfying fast data transmission and high power efficiency.

At the EEWebinar hosted by e4ds news on the 21st, Song Kyung-min, Director of the Power & Sensor Systems Division at Infineon Korea, introduced the concept of RF systems and the components and operating principles of RF front ends.

The 'RF (Radio Frequency)' system is a system that transmits and receives information using radio frequencies, and is a core technology that constitutes various wireless communication systems such as radio, television, mobile phones, wireless LAN, and satellite communications. A wireless communication system consists of a modem that modulates and demodulates digital signals, a transceiver (RFIC) that converts and amplifies digital-to-analog signals, an RF front end that determines whether a signal passes and amplifies it, and an antenna that transmits or receives radio signals.

Recent smartphones support high-speed data transmission based on various technologies. 'RX Diversity' technology is a method of receiving the same data simultaneously through two antennas and selecting the signal with better signal quality, that is, a high SNR signal. SNR means that the signal is stronger than noise.

There is also a 'MIMO (Multiple-Input Multiple-Output)' technology that can increase the downlink speed (throughput). MIMO is a method of increasing the downlink speed by receiving different data simultaneously through four antenna applications when the signal quality is guaranteed to a certain extent.

Smartphones used globally support approximately 30 frequency bands from 2G to 5G. Director Song said, “Smartphones have complex RF front-ends, and RF modules are implemented with basic elements such as filters, RF switch amplifiers, etc., so it is most important to understand the principles of each basic component.”

This Infineon webinar covered the RF switch and LNA functions, which are the core elements of the 'RF Front End (RFFE)'. RFFE is the process of transmitting and processing RF signals between the transceiver and the antenna, and is installed in all devices that support wireless communication, such as smartphones, laptops, tablets, and IoT devices. Director Song said, "When selecting RF products to configure RFFE, you should give priority to products with the best performance in the desired frequency band for stable wireless connection."

Basically, RFFE consists of basic elements such as filters, RF switches, low-noise amplifiers (LNAs), and power amplifiers (PAs). Filters select signals in the desired frequency band and block signals in other frequency bands. RF switches control the path of signals between multiple RF channels.

In particular, the 'LNA (Low Noise Amplifier)', which is a core element of RFFE, plays a role in amplifying small signals received through the antenna to an appropriate size. This is designed so that the amplifier of the receiving end generates as little noise as possible while amplifying the received signal so that the receiving end can process it. Since noise is mixed with various noises, it is not easy to capture only the desired signal, so the noise figure of the entire system must be improved, and the role of the LNA in the first stage of the receiving end is important.

Key parameters of LNA include loss and gain, noise characteristics, and linearity. “In the appropriate frequency band and bandwidth, these parameters determine the performance, sensitivity, and dynamic range of the entire RF system,” explained Director Song.

The explanation is that because LNA is nonlinear, the received signal is damaged by high frequency and modulation distortion, making it difficult to replicate the original signal, so a high-performance product must be considered for stable wireless connection in the entire RF system.

For example, when receiving a signal coming down from a satellite in a one-way communication such as a radio broadcast, an LNA is important to avoid interference from surrounding noise because a weak signal must be received from a satellite about 20,000 kilometers away.

“Infineon has many types of LNAs depending on various applications and frequency bands,” said Director Song. Major LNAs include products that switch the gain ON/OFF, support bypass mode, or are bank products in module form that integrate multiple LNAs.

In addition, Infineon offers various RF switch products according to power and number of input/output ports. Infineon also provides roadmaps for antenna tuning switch products. Director Song added, “Antenna tuning switches should be selected according to the type and characteristics of the antenna, and Infineon provides optimal antenna-related solutions and technical support through the antenna lab.”